Don’t try to use playing tug as a reward until your dog loves playing with you in different surroundings and different situations.
Practice playing with your dog in different places: in your own garden, on a walk, next to a sports arena, outside the mall... Add distractions to the game only after your dog loves playing with you alone in a quiet, familiar environment. When you can get your dog excited about playing with you even in the middle of a busy shopping mall parking lot, you will be able to do it also on the training field.
Have fun practicing - enjoy every moment with your best friend!